1. Field of the Invention
The present invention is generally directed toward concentrated acid detergent compositions and methods of using the composition, either as a concentrate or as a diluted use solution, to clean, sanitize, and remove scale from a soiled surface. More particularly, the acidic detergent compositions according to the present invention comprise a fatty alkyl-1,3-diaminopropane or salt thereof and optionally a lower alkyl sulfonic acid.
2. Description of the Prior Art
Adequate cleaning of food preparation surfaces is a necessity to ensure the safety of the food supplied to consumers. This is especially true for the dairy industry, food preparation and processing plants, including food and beverage plants, and particularly in the area of milk handling. Fresh milk must be immediately cooled and refrigerated after being obtained from the cow in order to prevent the milk from spoiling. Consequently, the piping systems which handle the flow of milk must be cleaned at least twice after each milking in order to remove milk soils so as to prevent contamination of the fresh milk supply during subsequent milking operations.
Turning now to FIG. 1, milk fat is made up of a wide distribution of alkyl triglycerides. Chain lengths labeled with a “:1”, “:2”, or “:3” represent a carbon chain containing one, two, or three unsaturated carbon-carbon bonds, respectively. The lower carbon chains (i.e., C8 and below) are generally water soluble. However, the higher carbon chains (i.e., C10 and above) are only slightly soluble or insoluble in water. Therefore, in order to clean a surface soiled with milk fat, ordinary warm water may be used to remove the lower carbon chain fats, while some kind of detergent is needed to assist with removal of the high carbon chain fats.
In addition to milk fat, milk also contains various soluble minerals (such as calcium) and proteins (such as casein and whey). Milk proteins at elevated temperatures tend to denature and tenaciously adhere to surfaces in layers. These layers of denatured milk protein are difficult to remove. The soluble minerals can combine with milk proteins to form scaling, also known as milk stone. Milk stone is generally insoluble in ordinary tap water and alkaline systems, but is soluble under acidic conditions. Conventionally, acid solutions of mineral acids and organic acids have been used to remove these scales.
Even if the milk fat, milk protein, and milk stone are removed from a surface, residual microorganisms may still be present on the surface. Therefore, some sanitization of the surface needs to be performed in order to reduce the level of microorganism populations to safe levels established by public health ordinances or levels proven acceptable by practice. A sanitized surface is, by Environment Protection Agency (EPA) regulation, a consequence of both an initial cleaning treatment followed with a sanitizing treatment resulting in a reduction in population of at least 99.999% reduction (a 5-log reduction) for a given microorganism. In order for a product to be certified under European Standard Method EN 1040 as a disinfectant or antiseptic, the product must demonstrate at least a 99.999% reduction (105 reduction) of Pseudomonas aeruginosa (ATCC 15442, CIP 103467) and Staphylococcus auerus (ATCC 6538, CIP 483) at 20° C. for 5 minutes contact time at the product's recommended use concentration. Similarly, for a product to be certified under European Standard Method EN 1276, as a sanitizer for food contact surfaces, the product must demonstrate at least a 99.999% reduction (105 reduction) in viable counts of Pseudomonas aeruginosa (ATCC 15442, CIP 103467), Escherichia coli (ATCC 6538, CIP 54127), Staphylococcus auerus (ATCC 6538, CIP 483), and Enterococcus hirae (ATCC 10541, CIP 5855) at 20° C. for 5 minutes contact time at its recommended use concentration under simulated clean conditions (0.3g/L bovine albumin) or dirty conditions (3 g/L bovine albumin).
The presence of residual food soil can inhibit sanitizing treatments by acting as a physical barrier that shields microorganisms lying within the soil layer from the biocide or by inactivating sanitizing treatments by direct chemical interaction. A complete cleaning process must address all three cleansing elements (cleaning, sanitizing, and descaling) in order to provide a hygenic environment for all food processing surfaces, especially milk processing surfaces.
The technology of cleaning in the food process industry has traditionally been empirical. For example, most dairies employ the clean-in-place (CIP) method, involving the flushing of contaminated equipment surfaces with cleaning solution(s). For example, the equipment is rinsed with lukewarm (110-120° F.) water, followed by a hot wash using a chlorinated alkaline detergent at 160-175° F., and lastly a cold acidic rinse using a mineral acid based composition such as phosphoric acid, sulfuric acid, and nitric acid based compositions.
Hypochlorite or chlorine bleaches are effective in degrading protein by oxidative cleavage and hydrolysis of the peptide bond. However, the use of chlorinated detergent solutions in the food processing industry is not problem-free. Corrosion is a constant concern, as is the degradation of polymeric gaskets, hoses, and appliances. Available chlorine concentrations must initially be at least 75 ppm, and preferably at least 100 ppm for an optimum removal of protein film (see, WO9947631). At concentrations of less than 50 ppm of available chlorine, protein soil build-up is worsened by formation of insoluble, adhesive chloro-proteins (see, Journal of Dairy Science, 53(2), 248-251, 1970). In Scandinavian countries, dairy farmers are able to obtain premium pricing for milk obtained with equipment that is not cleaned with chlorinated cleaning products.
Furthermore, chlorine concentrations are not easy to maintain or analytically discern in detersive solutions. The effectiveness of chlorine on protein soil removal diminishes as solution temperature and pH decreases. Also, chlorine can react with organic materials to form carcinogenic chlorocarbons, such as chloromethane, di- and trichloromethane, and chloroethane.
There exists a real and substantial need in the art for a non-chlorine, acidic detergent composition capable of cleaning, sanitizing, and descaling food preparation surfaces, particularly milking systems. In addition, there is a need for a detergent composition capable of performing all three cleansing processes (cleaning, sanitizing, and descaling) in a single step washing cycle.